How to Rebuild BorgWarner Transmissions

BorgWarner was one of the largest manufacturers of manual-shift transmissions in the United States. Ford and General Motors primarily made their own manual transmissions from the 1950s to the 1970s. Chrysler Transmission Development evolved into a company called New Process Gear. The majority of its transmissions were used in Chrysler products, but years later, that company was sold to competitors as well.

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/transmissions/how-to-rebuild-borgwarner-transmissions/

From left to right: Chrysler A833, ST10, and Muncie countergears. The A833 is longer because it incorporates the reverse idler as part of the gear. And of course, the A833 provides exceptional strength.

BorgWarner was different because it had no affiliation with any automobile manufacturer. The company sold its designs to any manufacturer as well as directly to the public via auto parts stores. It also made replacement parts for everyone’s transmissions, something only a few companies ever succeeded at. Companies, such as Republic Gear and Perfection Hy-Test, did the same thing, but oddly, today none of these companies produce any gears. This is important because you can find variations of certain BorgWarner transmissions in many makes and models.

T10 4-Speed History and Facts

Borg Warner produced many 3-speeds, such as the T85, T86, T87, T14, T15, and the T16. The first passenger- car 4-speed was the T10. In fact, it was the first American passenger-car 4-speed! It was based on the T85 design. Some T10 part numbers today still use the T85 prefix.

The T10 became an option in Corvettes in May 1957. Keep in mind that power levels of engines were climbing, and as a result, the T10 design had to change as well. Gears became wider, and alloys were changed. Unfortunately, there wasn’t an emphasis on documenting changes. For example, early third-speed gears have a bronze bushing and matching-diameter mainshaft, which do not interchange with later gears and shafts, but in GM versions only.

Early T10 transmissions were used in General Motors and Ford Products. As horsepower levels increased, GM designed the Muncie and Ford designed the Toploader. GM replaced the T10 with the Muncie in mid 1963. Ford kept both the T10 and Toploader in production at the same time. Certain optioned cars received a Toploader while others a T10. I still haven’t come across specific data that says which Ford cars got which transmission.

To accommodate increasing power levels, BorgWarner designed the Super T10. This transmission featured gears with a wide cut and a coarse pitch for better capacity. It eliminated a thrust bearing between second and third gear to tighten up on endplay issues and ditched alloy main cases in favor of nodular iron cases, which yielded a 50 percent increase in tensile strength. Ford and AMC used these “First Design” Super T10 transmissions from 1965 to the early to mid 1970s. BorgWarner also implemented its Power Brute Parts line. This gave individuals the ability to purchase upgraded components, gears, and complete replacement transmissions from their local speed shop or auto parts store.

These aftermarket transmissions offered special gear ratios. Again, this made the T10 a favorite among drag racers because the ratios gave people certain performance advantages over their stock units. The Super T10 gear ratios were designed to improve acceleration. You could get an ST10 with a 2.42, 2.64, 2.88, and 3.44 first gear.

The 9310 Nickel T10 gears can be identified by drill marks on the shaft. 9310 was a high-performance alloy used from the 1960s to the 1980s. Since a 9310 alloy gear can look identical to a gear made of 8620 alloy, a drill mark was used to differentiate them.

Super T10 GM Input Shafts. Note the various identification grooves and drill marks. The grooves identify the transmission ratio, and the drill mark indicates it is a 9310 alloy.

This is your basic early T10. It has a nine-bolt side cover and no external shifter shaft seals. BorgWarner used the same basic design for GM, Ford, and AMC cars. This is a T-10 from a GM car.

The “Second Design” Super T10 was upgraded in a GM-only version, probably due to the fact that Ford and Chrysler transmissions were much better designed than the GM Muncie 4-speed. In fact, it was quite common to adapt the Chrysler Hemi 4-speed to GM applications for dragrace use. The Second Design Super T10 added 26 splines to the input shaft and 32 splines to the output shaft to combat twisting. It increased the countershaft diameter from 7/8 to 1 inch, sleeved first gear (for improved oiling), used a cast-iron side cover to eliminate flex, and eliminated O-ring grooves on the forward shifter shafts to improve strength. The standard alloy ST10 was 8620, but the over-the-counter race units could be ordered with 9310 alloy gears for improved capacity.

The following is a quick reference guide for the ST10. Only firstgear ratios can be identified by the input-shaft ID grooves.

Gear Ratio Manufacturer

None 3.42 Pontiac

6 3.42 Chevrolet

5 2.88 GM

4 2.88 Aftermarket

3 2.64 All

2 2.43 All

A whole book could be written about T10 identification because many design changes occurred during production. In 1975, when horsepower levels dropped and gas mileage was a concern, GM replaced the Muncie with the ST10. The advantage was the ST10’s better firstgear ratios. These worked with more economical axle ratios, such as a 3.08. These Super T10s should not be confused with the replacement overthe- counter transmissions. The ratios and lightweight cases were designed for their intended use, making them weaker than the Muncie 4-speed but better suited to the axle ratios.

The Super T10 was used in GM vehicles from 1975 to 1983 as a 4-speed. The 1982–1983 F-Body Camaro/Firebird had an oddball version with a passenger-mount shifter, to centralize the stick to make it compatible with the 5-speed option. Doug Nash Engineering made a 2.88:1 first-gear version coupled to an automatic overdrive for the 1984–1988 Corvette; it was the 4+3. From looking at casting numbers in about 1982, Doug Nash Engineering purchased the rights to the T10 name and design. The design flaws of several components led to seal failures and made the 4+3 a very problematic transmission.

By late 1987 Doug Nash Engineering closed and Richmond Gear purchased the rights to the ST10 and all of Doug Nash’s designs. The buyout made sense because Richmond Gear was making most of the gears anyway. Today, the GM replacement ST10 4-speed can be purchased new from Richmond Gear, making it the longest running production 4-speed.

Rebuilding T10 4-Speeds

Although the T10 and Super T10 may look the same, internal differences require slightly different disassembly procedures. The build techniques are similar to the Muncie, and after a while, one becomes proficient at building this style of transmission. Like the Muncie, they have a side cover, a mid-plate-supported mainshaft, reverse shifter shaft in the tailhousing and a countergear supported by a pressed-in countershaft with loose needle roller bearings and thrust washers. The mainshaft and all the gears can be pulled out of the T10 transmission while the countergear and input shaft remain in place. The Super T10 countergear must be dropped first, or the front bearing removed, in order for the upper geartrain to clear the countergear during removal.

T10 Disassembly

Step 1: Remove Side Cover

Use a 1/2-inch socket and ratchet to remove the nine side-cover bolts and side cover. Keep all detents and shifter shafts in the cover. Simply lift both forks out of the case. Bag and tag shift forks for future use.

Step 2: Remove Front Bearing Retainer

Use a 1/2- inch socket and ratchet to remove the four bolts that fasten the front bearing retainer to the case.

Step 3: Take Off Snap Ring Spacer

Remove maindrive snap ring using snap-ring pliers and slide the spacer off the mainshaft.

Step 4: Remove Mainshaft Bearing

Some front bearings will slide off the input shaft; others may have to be pried off. If prying is required, you can use large screwdrivers or angled pry bars as prying tools.

Step 5: Drive Out Reverse Lock Pin

The reverse shifter shaft lock pin must be punched out from the bottom. Use a hammer and a zero size punch and carefully drive the pin out toward the top side of the case. This is a tapered pin and can ruin the case if removed in the wrong direction.

Step 6: Pull Shifter Out of Housing

Use a pair of pliers to pull the shifter shaft out and then disengage the reverse fork from the reverse gear. Be careful not to damage the shifter shaft threads. Sometimes it is better to leave the nut on the shaft and pull on the nut.

Step 7: Separate Tailhousing from Main Housing

Once the tailhousing bolts are removed, carefully pull the tailhousing away from the maincase. When you separate these components, the rear reverse idler gear may fall out. Some T10 transmissions have the lower two 5/8-inch bolts through the bolt into the main case. Others have them only bolt to the mid plate.

Step 8: Pull Mainshaft Out of Housing

Pry the mid plate away from the main case and pull the mainshaft assembly out using a screwdriver or small pry bars. Some versions have a retaining bolt that has to be removed first.

Step 9: Remove 3-4 Gear Synchro Assembly (Documentation Required)

There are only two snap rings that hold the whole geartrain together. Using a snap-ring pliers, remove the 3-4 synchro snap ring first. Once the 3-4 snap ring has been removed, slide off the 3-4 synchro assembly, third gear, 2-3 thrust washer, and second gear. To make assembly easier, make sure to properly identify and store the parts.

Step 10: A) Press Off 1-2 Gear Synchro and Parts

Disengage the rear snap ring using snap-ring pliers and move it out of the groove toward reverse gear. As you support the remaining parts on the 1-2 synchro, you can press the mainshaft through the 1-2 synchro, 1st gear, rear bearing, and reverse gear. Some T-10s may have a plastic speedo gear held on with a clip. This clip is simply pressed off by hand. If you have a steel speedo gear, you need to press the shaft through that gear as well.

B) Gear Synchros and Mainshaft Assembly

Here is a top view of how you can simply disassemble the mainshaft in two sections. You can see the order of the mainshaft gears and synchro rings.

Step 11: Remove Rear Bearing from Assembly

Spread the snap ring open with snap-ring pliers to remove the rear bearing. Sometimes the bearing drops out; other times a hammer is required to lightly tap the bearing out. Remove input shaft and parts.

Step 12: Remove Input Shaft

Lift out the input shaft and the forwardreverse idler gear and thrust from the main case, and pick out any loose needles and parts.

Step 13: Punch Countershaft Out of Case

Punch the countershaft out of the case from the front toward the back. This also knocks out the woodruff key located in the rear of the case.

Step 14: Take Out Countergear and Thrust Washers

Lift out the countergear and thrust washers from the main case. Needles in the countergear typically need to be replaced. New needles and spacers are in most rebuild kits, including a countershaft. The spacer tube is not included, so don’t lose it or throw it away.

The reverse fork is the only part you need to remove in the tail. It just pulls off the reverse arm by hand. I leave the reverse shifter shaft in the tail. The reverse shifter shaft can be pushed toward the outside with your hands to expose the O-ring seal, so it can be changed without having to disengage the shafts’ detent ball and spring.

Step 16: A) Remove Shifter Shaft

The last step of the disassembly and the first step of the assembly is the side cover. Remove the shifter shafts, change the O-rings, clean the cover, and put it back together. This keeps the small detents and interlock from getting lost.

B) Order of Parts for the Interlock System

Here is how the interlock system stacks in all T10 and Super T10 4-speeds: The balls, spring, and small pin are your detents. The large tube they fit in is actually the interlock.

T10 Assembly

Step 1: Install 1-2 Synchro Gear Assembly

Start your assembly by placing the 1-2 synchro assembly without the bronze rings on the mainshaft and the first-speed gear sleeve.

Step 2: Slide First-Gear Parts onto Mainshaft

To assemble the transmission, you basically reverse the disassembly process. Add the new first-gear synchro ring, first gear, and rear bearing retainer with a new bearing, and then replace the snap ring. Some parts may slide back into place; others may have to be pressed on. Rebuild kits have selective fit rings, and you fit the largest ring you can in the groove. Then slide on the reverse gear and press the speedometer drive gear. That completes the back portion.

Step 3: Install Second-Gear Parts (Professional Mechanic Tip)

T10s have a common second-gear jump-out problem. I replaced the second gear and also added a new 1-2 torque lock slider. To assemble, add the second gear ring, second gear, 2-3 thrust washer, third gear, third-gear synchro ring, and the 3-4 synchro assembly.

Step 4: Install Springs in Synchro Assembly (Precision Measurement)

Early T10s use a hollow stamped strut key. The tang of the spring fits inside the key. The spring on the opposite side has its tang located in the same key, but it loads in the opposite direction to give proper balance. Use this method for both synchro assemblies. Shown here is the 3-4 synchro assembly. Use a selective snap ring that gives you endplay between third and second gear between 0.010 and 0.030 inch. Try to keep toward the tighter spec.

Step 5: Position Reverse Fork (Professional Mechanic Tip)

Use assembly lube to hold the reverse idler thrust washer and reverse fork in place and shift it into the forward position, so it’s easier to connect it with the reverse gear. Notice that I’ve lubed the reverse-shifter-shaft O-ring as well. Pull the shifter shaft outward with your hand to replace the Oring, rather than removing it and having to deal with assembling the detent ball and spring.

Step 6: Orient Case Face-Down for Assembly

Lay the case face-down with the countergear installed. The input shaft is in place without the front bearing, with the pilot needles loaded. In addition, the forward-reverse idler and thrust washer are in the proper position.

Step 7: Install Mainshaft Assembly and Tailhousing

Reverse the procedure for installing the mainshaft assembly and tailhousing. The procedures are similar to the Muncie and Super T10 4-speeds. Apply assembly lube on reverse-shifter-shaft O-ring before tapping it toward reverse gear. Install tail bolts and speedo fitting, and make sure to put a drop of sealant on the reverse-shifter-shaft tapered lock pin.

Step 8:Install New Front Bearing and Parts

Install the new front bearing by tapping it down into place with a punch. Some bearings simply drop into place. Next install the snap-ring washer, and fit the largest snap ring that you can in the snap-ring groove.

Step 9: Bolt On Front Bearing Retainer

Install the front bearing retainer and make sure you apply sealant to the four bolts. GM T10s have no front seal, while Fords and AMCs do. So make sure to replace the seal as well. Most old seals easily pry out, an old socket can be used to press a new seal into place.

Step 10: Install New Shift Forks

It is a good idea to replace the shift forks with new ones. New forks help ensure the transmission does not fall out of gear. The transmission is shifted into second gear before the side cover is installed. Install the remaining 3-4 shift fork and side cover, and you are done.

Rebuilding Super T10 4-Speeds

As mentioned before, the Super T10 disassembles are similar to the T10 and Muncie 4-speed. The main difference is the sequence for removing the mainshaft and gears without using special pullers. Muncie and T10 mainshafts with all the gears intact can simply be pulled out.

In contrast, the ST10 has an upper third gear that cannot clear the lower countergear, but there are two ways around this problem. The first option is to remove the front bearing, which allows you to raise the mainshaft while attached to the input shaft over the countergear and take the whole upper assembly out. This technique requires a special puller to yank the front bearing off.

The second option is easier: Remove the countershaft and allow the countergear to drop down and away from the upper mainshaft. Once the countergear is dropped, remove the mainshaft and press the input shaft out through the front bearing using the case as a support. With some ratios, you are able to remove the input shaft with the front bearing attached from the inside, allowing you to firmly press it off using a hydraulic press.

ST10 Disassembly

Step 1:Remove Front Bearing Retainer

Take off the front bearing retainer and the side cover by removing the nine mounting bolts. Simply lift the shift forks out of the case. Before removing the tailhousing, use a hammer and punch to drive out the tapered pin from the bottom. Once removed, pull the reverse shifter shaft outward to disengage the reverse fork from the reverse gears. Unbolt and separate the tailhousing from the main case.

Step 2:Remove Reverse Idler Shaft

You rarely need to remove the reverse idler shaft because it seldom shows any sign of wear. If you do need to remove it, use a hammer and punch to drive the retaining pin cover and pin into the shaft.

Step 3:Reverse Idler Shaft

This is what the reverse idler shaft, pin, and pin cover look like when removed. To replace the shaft, simply insert the shaft back in the tail and punch the pin and pin cover in place from the outside. Apply sealant to the pin bore.

Step 4:Remove Mainshaft Assembly

With the tail and reverse idler removed, unbolt the mid-plate retaining bolt and punch the mid plate’s locating dowel into the case to remove it. Once the dowel has been removed, you can rotate the plate to expose the countershaft, so the shaft can be removed. Once the shaft has been removed, the whole geartrain has enough room to come out of the case.

Step 5:Press Off Front Bearing

Once the input shaft has been removed, use an old wrist pin as a press arbor and press off the front bearing. Here, I’m using an old case to support the gear.

Step 6: Replace Reverse Shifter Shaft O-Ring

It is not necessary to remove the reverse shifter shaft to change the O–ring seal. Push it all the way out, change the O-ring, and carefully push it back in a little.

Step 7: Remove 3-4 Synchro Snap Ring

Use a snap-ring pliers to remove the 3-4 synchro snap ring. Slide off or gently tap with a rubber mallet to remove the third gear and the 3-4 synchro assembly from the main shaft.

Step 8: A) Remove Reverse Gear from Mainshaft

Remove all snap rings, speedometer drive gear, and reverse gear from the mainshaft. With the rear bearing snap ring removed, support second gear with a press clamp and press the mainshaft through second gear, the 1-2 synchro assembly, first gear, first-gear sleeve, and the rear-bearing retainer in one step.

B)Mainshaft Parts

The basic components of the mainshaft have been disassembled, so you can see all the major parts.

Step 9:Remove Rear Bearing

Spread the retaining ring with snap-ring pliers and tap the rear bearing out while keeping the ring spread open.

Step 10: Press Out Countershaft (Professional Mechanic Tip)

The countershaft usually fits tightly in the Super T10, and I recommend using a shop press to remove it because driving it with a hammer and drift can spread the end. The countergear is loaded like the Muncie, and it has a spacer tube, four rows of needle bearings, and six spacer rings. Load the countergear with the spacer tube, spacer ring, needle row, spacer ring, needle row, and then spacer ring. Once this has been completed, flip the gear around and add a spacer ring, needle row, spacer ring, needle row, and sixth spacer ring. The outside rings should be recessed slightly in the gear.

Step 11: Check Countershaft for Binding

Pre-fit your countershaft in the countergear. Turn the shaft in the gear to check for rough spots because some shafts could have dings on them. Dings can be removed with a file. This procedure also aids in packing the needles.

ST10 Assembly

Step 1:Install Countergear

Install the forward countergear thrust washer to start the reassembly process. Use assembly lube to hold the washer in place.

Step 2:Insert Countergear in Case

With the main case facing down, insert the countergear. I’m holding the front spacer ring with my index finger, which keeps the needles from sliding out.

Step 3: Install Remaining Thrust Washer

Once the countergear is in position, slide in the rear thrust washer and engage its tab in the slot in the case.

Step 4:Position Countershaft in Case

Sink the countershaft far enough down by hand to make sure all the thrust washers line up. Press it back in place and stop about 3/8 inch before the final press and add the woodruff key. Then sink it home.

Step 5:Load Needles into Input Shaft

The input shaft needles look like this when loaded in place.

Step 6:Insert Input Shaft into Case

Drop the input shaft in place without the front bearing. The whole front case subassembly is facing down, and an old front case supports it. Add the forward reverse idler and its thrust washer and the fourth-gear synchro ring.

Step 7: Slide Second Gear and 1-2 Assembly onto Mainshaft

Slide second gear and the 1-2 assembly onto the mainshaft to start assembly. Notice the direction of the slider. The hub’s protruding edge is facing second gear.

Step 8:Press First 8 Gear onto Mainshaft

Flip the assembly around and press on the first-gear bushing. Some will slide on, but most require a mild press.

Step 9: Install First Gear onto Mainshaft

Flip the shaft around and slide the firstgear synchro ring, first gear, and first-gear thrust washer.

Step 10: Install Rear Bearing and Retainer

Drop into place or lightly tap down the rear-bearing retainer with a new rear bearing. Tap it down with a hammer and punch until it feels snug. When down all the way the snap-ring groove will be exposed.

Step 11: Install Rear Bearing Snap Ring

Make sure the rear-bearing’s 0.062-inch-thick snap-ring washer is installed first, and then fit in the thickest selective snap ring in your rebuild kit. The thickest ring will remove all endplay.

Step 12: Install Reverse Gear

Step 13: Install Third Gear

Install third gear, third-gear synchro ring, 3-4 synchro assembly, and its snap ring. Usually this ring is 0.087- to 0.091-inch thick. Always use a 0.087-inch one here. The last part is the needle-bearing thrust spacer. Hold this in place with grease. Notice the direction of the slider and hub.

Step 14: Main Case Rear Gasket

Assemble the ST10 with the main case on top of an old main case. Apply a small bead of sealant to hold the gasket in place and form a perfect seal.

Step 15: Preposition the 3-4 Slider

Before installing the mainshaft assembly, pull the 3-4 slider forward on the shaft. This allows the mainshaft to clear the countergear when installed in the case. Be careful not to let the strut keys fly out.

Step 16: Install Mainshaft Assembly (Important!)

This picture shows why the 3-4 hub is pulled forward to clear the countergear. I’ve reinstalled the dowel in the mid plate and will carefully mate the mainshaft to the input shaft. Make sure you line the fourth-gear synchro ring key slots with the strut keys before dropping the whole assembly in place.

Step 17: Install Retaining Bolt (Torque Fasteners)

Once the mid plate is sitting flush, tighten the retaining bolt to 30 ft-lbs.

Step 18:Install Rear Reverse Idler Gear

You really have to use a combination of RTV sealant and gaskets on this transmission because the two lower bolts never enter the main case. This area can warp because the main case does not support it.

Step 19: Insert Reverse Fork

Install the reverse idler shaft and thrust washer. Insert the reverse fork. Everything is held in place with assembly lube. Note that the reverse shifter shaft is moved forward in the reverse position.

Step 20: Lower Tailhousing onto Main Case (Professional Mechanic Tip)

By applying pressure with my palm, I’m holding up the reverse gear with my fingers and holding the reverse fork against the reverse gear. You catch the fork onto the reverse gear and gently lower the tailhousing in place, then push the reverse shifter shaft back in place.

Step 21: Fasten Tailhousing to Mid Plate (Torque Fasteners)

Once the tailhousing is flush with the mid plate, torque it down to 30 ft-lbs. Clean off excess sealant to give the build a “professional” appearance. Remember to install a new tapered pin, which should come in your rebuild kit.

Step 22: Install Front Bearing

Install the front bearing the same way as the mid plate. Use a punch and work the bearing down while holding the input.

Step 23: Install Outer-Case Parts

Once the bearing is in place, pull it out and install its outer-case retaining ring. Install the 0.062-inch bearing snap-ring spacer and then fit the thickest snap ring in front of it.

Step 24: Install Front Retainer Gasket(s) (Torque Fasteners)

Some bearing retainers require thicker gaskets. Our gasket sets include two front retainer gaskets. Place the bearing retainer on the transmission and use one gasket as a “feeler gauge.” If you can pull the gasket out while holding the retainer against the bearing, the retainer won’t seal and another gasket is required. Obviously, replace the front seal, use sealant on the four retainer bolts, bolt it up, and torque to 18 ft-lbs.

Step 25: Install Parts in Shift Cover (Professional Mechanic Tip)

More than likely the side cover will come apart when removing it. Install the shifter shaft seals first, and then install the shifter shafts with care to avoid pinching or rolling over the seals. Notice the sequence of the components. The outer sleeve is actually the interlock mechanism. The spring, balls, and pin are the detent mechanism.

Step 26:Check Operation of Shift Cover

After the detents and interlock are installed, check for smooth motion. You should bolt on the linkage arms so that the mechanism can’t fly apart. This is what it looks like in neutral, from the inside.

Step 27:Install Shift Cover (Torque Fasteners)

Install a bead of sealant on both sides of this side-cover gasket. The shift forks are lying on the sliders. You will have to put the transmission into second gear to get the 1-2 shift fork in place. You can leave it in second gear, but you must remember to shift the side cover into second as well. Once in place, install the nine side-cover bolts, and torque to 18 ft-lbs.

T5 5-Speed History

In 1985, I was doing a great deal of rebuilding for several new car dealers. A T5 transmission had come in with a broken third-gear section from a local Ford dealer. It was different from the normal T5s I had worked on. The first thing I noticed is that it no longer had bronze synchro rings but ones made of a fiber material similar to a clutch lining in an automatic. After doing some research and making a few calls, I found out that the T5 was upgraded to “world-class” standards.

There is a reason I placed this little bit of information first. It is important to understand that Borg- Warner, the manufacturer of the T5, was notorious for making unannounced and undocumented changes to production transmissions. T10 4-speeds, SR4 4-speeds, T50 5-speeds, and T4 and T5 transmissions all had a variety of design changes during a production run. Undocumented changes can cause service nightmares and the generation of misinformation. These changes are usually for the better. As certain designs fail when put into a production environment, new improvements are created to remedy warranty issues.

The T5 evolved from the T4, which evolved from the SR4 4-speed. The SR4/T5 concept was a departure from conventional T50 5-speed design. The SR4 stood for “Single Rail 4-speed.” The T50 5-speed used three rails. In fact, BorgWarner seemed to be the only company continuing to design single-rail shifting transmissions. Tremec did make the SROD (Single Rail Over Drive), but this design had many flaws, and new units went back to the three-rail system. When I researched the patents on the T5, it was interesting to find out that patents were approved for the fiberlined synchro rings and single-rail shifting mechanisms in 1981.

In a three-rail system, the shifter is connected to a shift rail, which selects three other rails, such as the 1-2, 3-4, and 5-reverse rails. In a single-rail system, one rail rotates and, by use of shift lugs, shifts individual 1-2, 3-4, 5-reverse synchros. The single-rail design, if implemented correctly, produces a lighter shifting mechanism as well as a very positive shift movement and feel. By using lightweight components, such as powdered metal interlocks and aluminum shift forks, shifting is much quicker.

The T5 transmission has many variations and is exported to China, Korea, and Europe for use in foreign vehicles.

While many people assume the T5 only came in Ford and GM variations, it was actually offered in many different spline configurations. Here is a large selection of T5 input shafts.

Too much sealant can get lodged in the housing bolt bores. When you screw in the bolts, hydraulic action may blow the case apart, especially if you use air tools.

The early non-world-class (NWC) T5s used a combination of flat roller bearings and thrust washers on the countergear. The input and output shafts used tapered cup-and-cone bearings. This design seemed to be influenced by the SR4 and T50, which both used a combination of flat roller bearings and thrust washers. By the nature of their design, flat roller/thrust washer systems cannot allow for preload. This allows gears to move around and get out of mesh.

Non-world-class boxes used allbronze synchro rings. The worldclass version allows for preload because it uses tapered bearings on the countergear as well. The drawback is that you have to use shims to set endplay or preload, and that requires more time. The world-class T5 uses fiber composite synchro rings on all gears except fifth. This is similar to material used in automatic transmission friction plates. All speed gears in world-class boxes ride on needle bearings except for fifth gear. This concept produces less parasitic drag and improves shift response. The use of fiber synchro rings and tighter tolerances requires lighter weight oils, such as Dextron III. Use of conventional gear lubes will ruin these transmissions.

The world-class spec did not replace the non-world-class design. In fact, both designs were produced at the same time. It boils down to how much money manufacturers wanted to spend. T5s were used in General Motors, Ford, AMC, TVR, Cosworth, Izuzu, Australian Holdens, Korean SSANGS, Nissan, Nisson, and Panther cars as well as Jacobson tractors and several utility vehicles. Beijing Warner in China also manufactured the transmission for Beijing Jeep. As of this writing, there are more than 260 T5 assembly part numbers.

T5 identification questions are common. It ranks number one in my popularity poll. So far, the basic T5 has been produced for 26 years, from 1982 to present. With so many variations available, it has become very popular for a multitude of projects and conversions.

Rebuilding the T5

There are several variations of the T5. Besides having the world-class and non-world-class specs, there are subtle changes in the world-class spec itself. The buildups cover world-class transmissions because of their current popularity. You may have heard of “Cobra”-style T5s, which have a tapered bearing in the input shaft as opposed to flat rollers. Some also have a reverse brake, which acts as synchro for reverse gear. T5s do not use any gaskets. The factory used black RTV, but I recommend Permatex 51813. A rebuild kit is a must for a T5 because individual components tend to cost as much as a whole kit. Variations are covered in the build up.

These are the very basic tools needed for a T5 build up. Access to a hydraulic press and a bearing clamp are necessary.

T5 Disassembly

Step 1: Remove Shifter-Cover Bolts

Remove the four shifter-cover bolts and pry off the shifter. Jeep units have five bolts.

Step 2: Remove Dowel Pin for Lever

Punching down the offset lever dowel pin disengages the lever from the rail.

Step 3:Properly Store Shifter Parts

Make sure the pin is completely removed from the lever, and all components are stored in the parts tray.

Step 4:Separate Tailhousing from Main Case

Remove the tailhousing’s bolts, pry the tail off, and remove the tail and offset lever in one step. Bolts have a 15-mm head. Be careful not to lose the detent ball and spring.

Step 5: Remove Top-Cover Bolts and Cover

Remove all the 10-mm cover bolts. Using a screwdriver to pry on the top cover to break the sealant bond. Some covers have pry tabs cast in; for others you have to pry carefully between the case and the cover.

Step 6:Remove Front Bearing Retainer

Remove all the 10-mm cover bolts. Using a screwdriver to pry on the top cover to break the sealant bond. Some covers have pry tabs cast in; for others you have to pry carefully between the case and the cover.

Step 7: Measure Front Bearing Race and Shims (Precision Measurement)

The front bearing race and shims are inside the retainer. Make sure you take a thickness measurement. If the shims have not been damaged, the same shim can be reused. Also, the original shim size makes a good starting point when beginning fresh with new gears.

Step 8: Remove Input Shaft and Parts

Remove the input by pulling it out of the front of the case. Rotate and pull at the same time to clear the lower countergear. Also extract the fourth-gear synchro ring and any flat thrust washers.

Step 9: A) Remove Needles and Flat Roller Plate

Remove all loose needles and the flat roller and store them safely. Some needles may fall out into the case.

B) Main Needles for T5

The three types of main drive needles in T5 transmissions are: (from the left) 15 needles and a spacer, a caged roller found in most European T5s, a tapered cup, and a cone bearing in later-Cobra-style Ford T5s.

Step 10:Drive Out Fifth-Gear Fork Pin

Support the fifthgear fork with a socket, and drive out the fork’s roll pin with a hammer.

Step 11: A) Remove Fifth-Gear Assembly

Flip the transmission on its face. This makes it easy to remove the fifth-speed assembly snap ring and pry off the assembly and fork. Pry between the fifth gear and the case.

B )Fifth-Gear Synchro Retainers

The left fifth-speed synchro retainer is a standard T5 type. The one on the right is the reverse brake style.

Step 12:Remove Fifth-Gear and Reverse Rail

With the fifth-gear fork and synchro assembly out (1), you can remove the lower fifth gear (2) and rear mainshaft bearing race (3).

Step 13: Prep for Mainshaft Removal (Professional Mechanic Tip)

The 0.80-inch OD sets and aftermarket fifth gears are larger than the rear bearing race. You can’t remove the rear race and mainshaft. It is next to impossible to remove upper fifth gears with a puller, so I drop the countergear, push the upper gear train in the case, and cut the bearing race in to spots 180 degrees apart. This allows me to gain the clearance needed to remove and lift the mainshaft out of the case once the rear race is gone.

Step 14:Lift Mainshaft from Case

Once the mainshaft bearing race has been removed, you can lift the geartrain out of the top. Notice that you don’t need to mess with the fifth-reverse lever.

Step 15:Remove Speedometer Drive

Press on the clip to release the speedometer drive gear. Here, the inset shows later-model speedometer reluctors, which also act as a secondary retainer for fifth gear. You must remove the reluctor first, before removing the fifth-speed snap ring.

Step 16:Press Gears Off (Important!)

Never try pulling fifth gear off or using press clamps against it. Use press plates to support under first gear (where you can get optimum support), and press first through the upper fifth off.

All these parts will come off in one action by using a press.

Step 17: Remove Gears and Bearings

Flip the geartrain around, support with press clamps under third gear, and press the mainshaft through the 3-4 synchro and third gear. Units with the Cobra pocket bearing require you to press under the bearing first, remove the bearing, then remove the 3-4 synchro snap ring before doing this step.

Here are all the parts that come off the mainshaft when this step has been performed.

Step 18: Remove Second Gear and Parts

Laying the parts out on a bench in the order in which they were removed helps you to reassemble it more easily.

Step 19: Remove Second Gear Thrust Washer and Synchro Ring

Use a small screwdriver to start unwrapping the spiral lock retaining ring that holds the secondgear thrust washer and synchro ring in place.

Step 20: Take Off 1-2 Slider

Sometimes the 1-2 slider falls off from the first gear side. It is the final part to slide off; don’t lose the keys and springs. My finger is holding a small pin, which keeps the first-gear sleeve from spinning. Don’t lose that either. Later units use a tiny ball bearing. So be careful.

Remove the four countergear retainingplate bolts, the plate, and shim. Use your press clamps to clamp under the rear bearing. This elevates the countergear just enough to press it through the rear bearing. Use an aluminum drift on the back side of the counter to press it off.

Step 22: Remove Countergear from Main Case

Once the rear bearing is removed, the countergear comes out of the main case. Again, notice that the fifth-reverse lever was never removed.

Step 23: Break Off Counterbearing

There is no way to remove the front countergear bearing without destroying it. So I break off the cage of the bearing with a screwdriver, which gives me a solid lip for fastening my press clamps.

Step 24:Press Off Gear (Professional Mechanic Tip)

Support the gear on an old transmission case and press it through the front bearing race with an old idler shaft. Now both bearings are removed from the countergear. Your T5 is now completely apart.

Now that the T5 is more than 20 years old, some units may have already been rebuilt or assembled with a variety of parts. With more than 265 T5 models, you can mixand- match cases and gearsets to a point. If colored sealants (red, blue, or clear) have been used, it’s tell-tale sign that the T5 has been taken apart. It is not necessary to completely disassemble a T5. The top cover need not be disassembled and lower countergear need not be removed unless these components in the cover, the countergear, or its bearings need replacement.

There are several procedures that you may or may not have to do. The first optional procedure is to remove the reverse idler gear and shaft, which are simply held in with a roll pin. The other is removing the front countergear bearing or front input shaft bearing since these bearings actually never fail. If the countergear isn’t broken, you may want to leave the whole gear still in the case and avoid that step altogether, if for example, you are just changing synchro rings.

T5 Assembly From the Ground Up

In my shop, we deburr all the gears in the T5s we build. If they are used for heavy-duty street/strip use, we add one of our countergear stabilizer plates. We designed the plate to keep preloads constant as well as add steel support for the rearcountergear bearing race. Aluminum copies really don’t accomplish anything and are a waste of money. The T5 requires only two measurements for assembly. I’ve found that if you preload the countergear with 4 to 6 inchpounds of drag, and you keep the upper geartrain to more than 0.003-inch to zero endplay, you will extend the life of your T5 compared to factory specs, which call for endplay.

T5 Assembly

Step 1:Apply Sealant to Front Countergear Bore

Starting with the bare case, use Permatex 51813 sealant to coat the front countergear bearing bore. The fifthreverse shift rail Welch plug does not need to be removed. However, if it was removed, now is a good time to reinstall it.

Step 2: Install Front Countergear Bearing Cup (Important)

Install the front bearing cup carefully. Seat it by hand first then tap it in gently to avoid ripping the O-ring.

Step 3: Install Fifth-Reverse Shift Arm and Clip

Install the fifthreverse shift arm and clip. The pin that it rides on doesn’t have to be removed, but if you do remove it, reinstall it with red liquid thread locker.

Step 4: Install Reverse Idler Gear and Parts

For clarity remove the arm, but install the reverse idler gear, shaft and O-ring, and pin it back in place. Install the roll pin so that it is centered in the shaft.

Step 5: A) Install Countergear

Press on the front countergear bearing using a simple socket and hammer. Remember to place the rear bearing on the countergear after it is installed in the main case.

Simply tap the bearing on with a small punch slowly, and work evenly from side to side. Yes, a long pipe would work as well, but for the one-time rebuild, this works fine.

B) Retainer Plates

Here are a standard retainer plate (left) and our beefed-up stabilizer (right). I have found that under heavy load, the factory plate stretches and that allows for the countergear to move around too much. It is not needed for a standard rebuild. I designed this plate to be made of steel; cheap copies made of aluminum will not work.

Step 6:Install Countergear Shim

I’m using a 0.132- inch-thick shim here. Lately I seem to average 0.125 to 0.135 inch. Our new Peel-’n-Place shims use a solid 0.080- inch shim and a peelable 0.080-inch shim in 0.005-inch increments.

Step 7:Install Retaining Plate

Whatever plate you decide to use, shim it to yield 4 to 6 inch-pounds of drag. Use an inch-pounds torque wrench to measure this. If you’re doing it by “feel,” the countergear should have no endplay and some smooth drag to it.

Step 8: Clean Up Shift Rails

Deburr and polish all shift rails. These rails have a tendency to get chewed up from dirt in the case bores.

Step 9:Reverse Fork Installation

Variation A: Insert reverse idler fork, return spring, and insert rail. Once in place, turn the rail so the roller engages the fork. Variation B: This should be done before any gears are in case. Insert wrap spring on fork. Slip the spring through reverse arm and fasten to case post. Once in place, insert fifth-reverse arm Torx bit shaft. Then insert reverse idler gear assembly and, finally, fifth-reverse shift rail.

Step 10:Locate Slider Strut Slots (important)

Later units have specific locations for strut keys. Make sure the center key slot lines up with the key slot in the synchro hub. This applies to the 1-2 as well as the 3-4 synchro assemblies. Install the 1-2 slider with the fork groove facing toward the front and install the three strut keys and two springs.

Step 11:Pre-lube Synchro Rings

Step 12: Install Second Gear Thrust Washer and Retaining Ring

After installing the secondgear synchro ring, install the second-gear thrust washer and spiral lock retaining ring. A small screwdriver can do this quite well.

Step 13:Install Second Gear and Parts

Install the second gear first, then the bearing spacer, and the needle bearing. This method prevents the tiny spacer from getting caught under the gear and bent.

Step 14: Install 2-3 Thrust Washer and Snap Ring

Install the 2-3 thrust washer and its snap ring.

Step 15:Install Third Gear and Parts

Install third gear and its synchro ring first, then the third-gear needle spacer, and the needle bearing.

Step 16:Install 3-4 Synchro Assembly (Professional Mechanic Tip)

Install the preassembled 3-4 synchro assembly. Use an old socket and smack it down. If building a Cobra-style T5, install the 3-4 hub snap ring and press on the pocket bearing. Use a 1/2-inch socket to either press the bearing on or tap it down with a hammer. For complete synchro ring assembly instructions, refer to page 26.

Step 17:Install First Gear Sleeve and Pin

Flip the mainshaft over and insert the first-gear sleeve anti-rotation pin by sliding it over the shaft. Right: Later units use a ball.

Step 18: Install First Gear and Sleeve Assembly

Install the first-gear roller bearing and sleeve assembly and make sure you catch the rotation pin/ball in its slot.

Step 19:Install First Gear and Rear Bearing

Install first gear and the rear bearing. Press on the upper fifth gear as well. If you have a 0.80- inch OD fifth gear that doesn’t fit through the rear bearing race, install the mainshaft assembly in the case without the fifth gear on the shaft.

Step 20:Install Fifth Gear (important)

Here is the common approach to installing fifth gear. Inset: This is how you press on a fifth-speed gear when the gear does not fit through the rear bearing race. The rear bearing race is held in place with a home-made retainer. The whole transmission is fitted into the press. I’m pressing against the tip of the mainshaft.

Once the fifth gear has been installed, always use a snapring pliers to install the fifth-gear snap ring. For some reason, people often leave this step out

Step 21: A) Assembled Geartrain

The completed T5 geartrain looks like this. Notice the direction the synchro sliders are facing and how the 3-4 slider’s tapered edge is facing toward the front.

B) Fifth Gear Synchros

The fifth gear on the left shows the later-designed and stronger synchro-engagement tooth design than the gear on the right.

Step 22:Replace Pads on All Shift Forks

These inexpensive plastic pads on the shift forks simply snap on and off and should be replaced. This stage is a good time to replace all pads on all forks.

Step 23: Install Lower Fifth Gear and Synchro Ring

Drop the lower fifth gear and its new synchro ring in place. Install the fifth-speed fork in the fifth-gear synchro assembly, and slide the whole assembly into place. Notice the orientation of the slider, hub, and fork.

Step 24: Install Fifth-Gear Spacer and Retaining Ring

Install the fifth-gear spacer and retaining ring. With the reverse brake variation, install the reverse synchro ring, brake cone, washer, and retaining ring. This is also a good time to install a new oil funnel.

Step 25: Install Reverse Fork Retaining Pin

With a punch and a hammer, drive in the reverse fork retaining roll pin until it is flush with the top of the fork. Inset: The left fork is the newer style, which adds more support to the early fork on the right. New forks sell for under $20, so they are a worthy upgrade.

Step 26:Install Speedometer Gear

There are many T5 speedometer drive-gear variations. The more common ones simply fasten with a spring clip. Others use a ball and snap ring.

Step 27: Prepare Input Shaft for Installation

Press on the input front tapered bearing. Load the inside needles and flat roller bearing. Use assembly lube to hold them in place. Pocket bearing units simply must have a race pressed in.

Step 28: Install Bearing on Input Shaft

If you don’t have a press, gradually walk the bearing down with a punch and a hammer, tapping on the punch from side to side.

Step 29:Insert Main Drive-Thrust Washer and Parts

Install the main drive-thrust washer and needle spacer. Some older units didn’t have a spacer. It keeps the needles from skewing, so it is a good idea to install it on every unit. Pocket bearing units don’t require this step or parts.

Step 30: Slide On Fourth-Gear Synchro Ring

Install the new fourth-gear synchro ring. Hold it in place by putting assembly grease in its key slots and press it into the synchro assembly.

Step 31: Align and Install Input Shaft

The input shaft has a clearance slot on its engagement teeth, which clears the countergear. Align the clearance space with the countergear and insert the input shaft into the main case.

Step 32:Inspect Shift Lugs (Critical Inspection)

Before assembling the top cover, inspect your shift lugs. Shift lugs often stretch out. Example A shows a good lug fit, while Example B shows a poor fit. A poor fit will cause strut keys to pop out and cause over-shift issues.

Step 33: Punch Out Shift Finger Rail Pan (important)

Since all that is required to disassemble the top cover is to punch out the shift finger roll pin and pull it all apart, many forget how it goes back together. Notice that the 3-4 fork lug sits lower than the 1-2 fork lug. Also notice the position of the shift finger’s roll pin. The front of the cover is to the left.

Step 34: Orient Interlock Plate (important)

Also, the location of the interlock plate is an important detail because it is very easy to install it upside down. The correct way is shown here.

Step 35:Apply Sealant to Main Case

Apply sealant on the top of the main case, on the tailhousing for the tail section, and on the front retainer. This step ensures that sealant is not displaced during assembly, which could cause a potential leak.

Step 36:Install Top Cover (Torque Fasteners)

The fifth-gear-reverse arm rests on top of the other lugs. Install the top cover by moving it away from yourself to clear the fifth-reverse arm, and then toward yourself and down.

First install both dowel bolts, and then the remaining eight bolts, to fasten the cover. Torque the bolts to 12 ft-lbs.

Step 37:Insert Detent Ball in Tailhousing Track Plate

Use assembly grease to hold the detent ball in the tailhousing’s track plate.

Step 38: Slide Trail Assembly onto Main Case (Torque Fasteners)

Apply sealant to the tail, loaded the detent spring in the offset lever, and install a new shifter bushing. Both are held in place with grease. Position the offset lever’s spring on the detent ball in the tail in the neutral position. Slide the tail on while applying a firm downward pressure on the offset lever. Torque the tail’s eight bolts to 25 ft-lbs.

Step 39: Shim Input Shaft (Precision Measurement)

The last step is setting up input-shaft clearance. Shoot for zero endplay with about 0.003-inch preload max. Peelable T5 shims manufactured by 5speeds.com make the job a snap. Do not install the seals. Once the endplay is set, seat both input and output shafts with a rap of a rubber mallet, then recheck for endplay.

Step 40: Install Seals and Retainer (Torque Fasteners)

Once you’re happy with the endplay, install the front seal, front retainer, and rear seal. Older transmissions have aluminum retainers that gall and wear fast. Upgrade to a newer cast-iron retainer. Torque the four bolts to 20 ft-lbs.

High-Performance T5

In 1995 I thought the T5 would make a great road-racing transmission for cars up to 400 hp. To me there were plenty of transmissions rated for more than 500 hp, and I felt the use of these big transmissions in 200-hp applications would simply rob too much power. The JT5 was created for a Jaguar race team in late 1995. Jaguars required a very short transmission, so basically I shortened the T5 from 24 to 15 inches using a custom-designed mainshaft and tailhousing. It would only see 400 hp. In 10 years, who knew that because of the JT5 size, they would be installed in everything from Ferraris, Aston Martins, Volvos, Morgans, MGBs, and many other makes. The JT5 has been installed in more than 800 street Jaguars and has sparked interest in overseas companies to now make similar products based on the T5 platform.

Here is a JT5 Enduro transmission built with G-Force’s new heavy-duty T5 case. You can get this case in standard Ford Toploader, GM, and Ford T5 bolt patterns.

G-Force makes cast-bronze and billet-machined shift forks for the T5. This transmission has a JT5 Enduro gearset loaded in a G-Force case.

The need for better gear ratios and stronger gears led to a complete redesign, featuring dog-ring-style gears, modular countergears, and beefed-up mainshafts. All contained better grade alloys with all gears riding on needle bearings.

By 2001, G-Force Transmissions came on the scene, concentrating on the street/strip market. Its T5 is a great-shifting transmission. G-Force has made heavy-duty 9310 helical replacement gears, helical dog-ring gears, and straight-cut gears as well. They claim that these gearsets, if set up correctly, can handle more than 500 hp.

By late 2005, Liberty’s High Performance Products took over our Enduro design and made a gearset suited for drag racing. Unlike other aftermarket T5 gearsets, the Enduro mainshaft is much larger in diameter and eliminates the common areas of flex and stress. It is the only gearset that doesn’t duplicate the poor factory mainshaft design.

Written by Paul Cangialosi and Posted with Permission of CarTechBooks

GET A DEAL ON THIS BOOK!

If you liked this article you will LOVE the full book. Click the button below and we will send you an exclusive deal on this book.